ABSTRACT
The relationship between and chamber pressure in displacement vane pump was examined. Results are follows: (1) The vane tip clearance increases with the x-axis eccentricity, having a maximum value of 0.8 mm. (2) As the x-axis eccentricity decreases, a smooth pressure transient is difficult to obtain. Consequently, the y-axis eccentricity in a variable displacement vane pump must be adjusted, especially in the cut-off and dead-head conditions. (3) Vane detachment and re-attachment angles are both delayed with an increase in the y-axis eccentricity due to precompression in the pumping chamber. No vane jumping occurs at a high rotational speed when ey=+0.2 mm. (4) Pumping chamber pressure measurements clearly showed that vane detachment is
ex = 2.5 mm ev=0mm n= 1200 rpm
FIGURE 12 Vane tip locus determined by eddy current sensot· and pumping chamber pressure at various values of P d
caused by excess pre-compression in the dead-volume zone.
